Thirty years ago, the scientist James Lovelock worked out that the Earth possessed a planetary-scale control system which kept the environment fit for life. He called it Gaia, and the theory has become widely accepted. Now, he believes mankind's abuse of the environment is making that mechanism work against us. His astonishing conclusion - that climate change is already insoluble, and life on Earth will never be the same again.

The world has already passed the point of no return for climate change, and civilisation as we know it is now unlikely to survive, according to James Lovelock, the scientist and green guru who conceived the idea of Gaia - the Earth which keeps itself fit for life.

In a profoundly pessimistic new assessment, published in today's Independent, Professor Lovelock suggests that efforts to counter global warming cannot succeed, and that, in effect, it is already too late.

The world and human society face disaster to a worse extent, and on a faster timescale, than almost anybody realises, he believes. He writes: " Before this century is over, billions of us will die, and the few breeding pairs of people that survive will be in the Arctic where the climate remains tolerable."

In making such a statement, far gloomier than any yet made by a scientist of comparable international standing, Professor Lovelock accepts he is going out on a limb. But as the man who conceived the first wholly new way of looking at life on Earth since Charles Darwin, he feels his own analysis of what is happening leaves him no choice. He believes that it is the self-regulating mechanism of Gaia itself - increasingly accepted by other scientists worldwide, although they prefer to term it the Earth System - which, perversely, will ensure that the warming cannot be mastered.